Interfacial micromechanics in model composites using laser Raman spectroscopy

1993 ◽  
Vol 440 (1909) ◽  
pp. 379-398 ◽  
Keyword(s):  
Shear Stress ◽  
Carbon Fibre ◽  
Load Transfer ◽  
Interfacial Shear Stress ◽  
Stress Transfer ◽  
Fibre Surface ◽  
Interfacial Shear ◽  
Laser Raman Spectroscopy ◽  
Laser Raman ◽  
Balance Of Forces

The mechanisms of load transfer in single carbon-fibre/epoxy-resin model composites, are investigated. The composites are subjected to incremental tensile loading and the fibre fragmentation process is continuously monitored. The fibre strain distribution along the fibre fragments is derived through the Raman spectrum of the carbon fibre and its strain dependence. In turn, the interfacial shear stress distribution is evaluated by means of a balance of forces analysis. The effect of fibre surface treatment and fibre modulus upon the stress transfer profiles and the distribution of the interfacial shear stress along the fibre, are also examined. Finally, the importance of parameters, such as, fibre/matrix debonding and interphasial yielding at the vicinity of fibre breaks, is discussed.

An Analytical Model of Stress-Transfer in the Nano-Composites with Debonding Interface

2010 ◽  
Vol 163-167 ◽  
pp. 4599-4603
Author(s):  
Wen Liang Zhu ◽  
Dong Mei Luo ◽  
Ying Long Zhou ◽  
Wen Xue Wang
Keyword(s):  
Shear Stress ◽  
Analytical Model ◽  
Load Transfer ◽  
Polymer Matrix Composites ◽  
Axial Stress ◽  
Interfacial Shear Stress ◽  
Stress Transfer ◽  
Matrix Composites ◽  
Load Transfer Efficiency ◽  
First Time

An improved shear-lag analytical model has been established to study stress transfer in carbon nanotube (CNT) reinforced polymer matrix composites with and without debonding interface. The Poisson’s effect and radial effect of matrix is considered in the model for the first time, and a simplified 2D representative volume element (RVE) is modeled using a four-phase composite composed of matrix, nanotube, bonded, and debonded interfaces in this analysis, and the axial stress for CNT and matrix and interfacial shear stress along the CNT is predicted. The results show that load transfer efficiency in CNT reinforced composites is affected by the debonding length, and the abrupt change of shear stress is existent at the tip of debonding interface.

Cohesive-Shear-Lag Modeling of Interfacial Stress Transfer Between a Monolayer Graphene and a Polymer Substrate

2015 ◽  
Vol 82 (3) ◽  
Author(s):  
Guodong Guo ◽  
Yong Zhu
Keyword(s):  
Fracture Toughness ◽  
Shear Stress ◽  
Interfacial Shear Stress ◽  
Stress Transfer ◽  
Interfacial Shear ◽  
Interfacial Stress ◽  
Monolayer Graphene ◽  
Shear Lag ◽  
Shear Lag Model ◽  
Lag Model

Interfacial shear stress transfer of a monolayer graphene on top of a polymer substrate subjected to uniaxial tension was investigated by a cohesive zone model integrated with a shear-lag model. Strain distribution in the graphene flake was found to behave in three stages in general, bonded, damaged, and debonded, as a result of the interfacial stress transfer. By fitting the cohesive-shear-lag model to our experimental results, the interface properties were identified including interface stiffness (74 Tpa/m), shear strength (0.50 Mpa), and mode II fracture toughness (0.08 N/m). Parametric studies showed that larger interface stiffness and/or shear strength can lead to better stress transfer efficiency, and high fracture toughness can delay debonding from occurring. 3D finite element simulations were performed to capture the interfacial stress transfer in graphene flakes with realistic geometries. The present study can provide valuable insight and design guidelines for enhancing interfacial shear stress transfer in nanocomposites, stretchable electronics and other applications based on graphene and other 2D nanomaterials.

scholarly journals Analysis of Load Transfer Behaviour and Determination of Interfacial Shear Strength in Single-Fibre-Reinforced Titanium Alloys

2007 ◽  
Vol 16 (5) ◽  
pp. 096369350701600 ◽  
Author(s):  
Theodore E. Matikas
Keyword(s):  
Load Transfer ◽  
Elevated Temperatures ◽  
Interfacial Shear Stress ◽  
Stress Transfer ◽  
Single Fibre ◽  
Interfacial Shear ◽  
Matrix Composites ◽  
Titanium Matrix ◽  
Nondestructive Technique ◽  
Titanium Matrix Composites

The effect of interfaces on load sharing behaviour has been evaluated by performing single-fibre fragmentation (SFF) experiments and analysis of titanium matrix composites at ambient and elevated temperatures. Fibre breaks were monitored by acoustic emission sensors, and the break locations were determined in-situ by an innovative ultrasonic non-destructive evaluation technique. Data analysis of SFF testing was performed using the Kelly-Tyson model. The length of fibre fragments and distribution were determined using innovative nondestructive technique. This study demonstrates that composite processing conditions can significantly affect the nature of the fibre/matrix interface and the resulting fragmentation behaviour of the fibre. Further, thermal micro-residual stresses, generated during the fabrication process and in-service due to the difference in thermomechanical characteristics of the model composite's constituents, play a major role influencing the interfacial shear stress transfer behaviour in single-fibre titanium matrix composites.

Effect of interfacial debonding on stress transfer in graphene reinforced polymer nanocomposites

2017 ◽  
Vol 27 (7) ◽  
pp. 1105-1127 ◽  
Author(s):  
Meghdad Heidarhaei ◽  
M Shariati ◽  
HR Eipakchi
Keyword(s):  
Shear Stress ◽  
Polymer Nanocomposites ◽  
Applied Stress ◽  
Volume Fraction ◽  
Axial Stress ◽  
Interfacial Shear Stress ◽  
Stress Transfer ◽  
Interfacial Shear ◽  
Zone Model ◽  
Reinforced Polymer

A shear-lag analysis hybrid cohesive zone model is employed to investigate the stress transfer from polymer matrix to the graphene by considering the interfacial damage and debonding phenomena in graphene reinforced polymer nanocomposites. The applied stress can produce three cases for interface treatment: entirely intact, damaged and debonded. By using analytical derived relations, the distribution of axial stress in the graphene and interfacial shear stress at the three-mentioned states is determined and the applied stress to the nanocomposite which leads to damage and debonding initiation at the interface is evaluated. In addition, a sensitivity analysis is performed and the effects of graphene length, interfacial shear strength and graphene volume fraction on the axial stress of graphene, damage and debonding threshold stress along the interface and interfacial shear stress are studied. The results show that after applying a stress called second critical stress, the stress transfer between graphene and matrix at the bulk of graphene length (about 75% of the interface) stops due to debonding of this zone.

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